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Hardware Multiplier

4 x 4 hardware multipllier!

OK, it ain't much, and I have no idea if it will work, except watching the bits all follow their little truth tables in my mental simulator ... I drew this in Xiilinx, but have no idea yet how to run a simulation, or dump it to the bitstream that could program the chip (BTW, did I say that a prospective client has sent me a "CPLD 95XL DEMO BOARD"? He sent it to me in case I got this one gig, which I think that by chatting him up on the telephone, I inspired him to find a better, cheaper faster way, and so talked myself out of a job, but as a sort of gratituity, I think he's going to let me keep the board. And the Software. :-)

Anyway, there was talk of a hardware multiplier, and I've wanted to do this since I grasped the concept of "barrel shifter", so I've drawn a schematic - the Xilinx S/W doesn't have an obvious "save as", so I screencapped it in PSP. The little labels on the inputs to the AND gates are 'multiplier(3:0)', expanded, as are the inputs across the top. The multiplier comes in on the left, and the product comes out the bottoj.

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Anybody up to callng my bluff? ;-P ;-P ;-P

Cheers! Rich

Reply to
Rich, Under the Affluence
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Your gif was almost illegible.

You know, you can just imply a hardware multiplier in verilog or VHDL, and I'm pretty sure the tool will make the inference for you.

If you want me to test your multiplier, can you put up the design files?

There is a free version of the Xilinx software (webpack), by the way, which will easily handle small designs like this. And there is a free simulator, too, which you download separately. It's Modelsim, XE (xilinx edition).

In fact, you could do a fair amount of design work with nothing more than this.

--Mac

Reply to
Mac

Sorry for that. You shouldn't really need to read the lables to see that it's and gates and 1-bit adders, but the top four lines are multiplicand(3:0), the four down the left are multiplier(4:0), with multiplier(0) on top, and the 8 outputs at the bottom are product(7:0). The labels on teh intermediate and inputs are just multiplier(3:0), because I didn't want to squeeze in wires - they just stairstep their way down.

Oh, yeah, but that's not what I wanted to do. I wanted to see if I could slap one together with adders and gates. :-)

Well, I can, but I'm not very proud of them - I should have had the tutorial open on the side, because there's some stuff I've left out and some stuff I have yet to do. I was kind of jazzed at getting the schematic this far, because building a hardware multiplier (or even just drawing one) has been a dream since I heard of such a thing. :-)

Yeah, that's exactly what I'm using, in schematic entry mode. Like I said, I still have some RTFM to do to get into any more depth.

Exactly - and the thing that prompted it is that this client sent me a little "Demo Board" about 2 1/2" x 4 1/2" with an XC9572 on it and 64 I/O header pins. :-)

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So, when I get a round tuit, I'll not only simulate this thing, but bring the inputs out to pins, and use the LEDS for outputs, and actually run it!

Cheers! Rich

Reply to
Rich Grise

Nope, the job is still sitting there, like an unscratched itch. I just haven't written up the spec and fired off the P.O. yet. :>)

--
 Thanks,
    - Win
Reply to
Winfield Hill

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